Figure 3. Fluorescence confocal microscopic images of cells after ultrasound-induced cytosolic delivery of β-galactosidase (β-Gal). (A) DLD1 cells treated with phase-change nano-droplets (PCNDs) carrying β-Gal and ultrasound, (B) those treated with β-Gal-carrying PCNDs without ultrasound, and (C) those treated with PCNDs not carrying β-Gal and ultrasound were observed after staining with a fluorescent substrate for β-Gal (TokyoGreen-βGal) and a endosomal and lysosomal staining dye (Lysotracker). (D) Intact cells were also observed as the control in the same way. The fluorescence images for TokyoGreen-βGal (green) and Lysotracker (cyan) were merged along with the differential interference contrast images. Scale bar: 25 μm.